This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The formation and maintenance of synapses are fundamental bases for the nervous system. Our previous research showed that the interaction of voltage-gated calcium channels (VGCCs, PQ- and N-type) and synaptic laminins is required for organization of active zones (AZs) in motor nerve terminals. The role of presynaptic VGCCs in synaptic transmission is well established but a role as a receptor to organize AZs is a new concept. We hypothesize that VGCCs at nerve terminals are important scaffolding proteins to organize AZs, and aim to gain insight into the mechanism of AZs organization at synapses by these three specific aims. (1) We will systematically screen the direct interaction of VGCCs and AZ proteins biochemically to seek intracellular mediators of the AZ organizers. In addition, we will access the functional role of such interaction for the presynaptic differentiation using cultured primary motor neurons and electrophysiological recordings. (2) We will analyze mice lacking the N-type VGCC and both N/PQ-type VGCCs to assess their role in presynaptic differentiation. (3) We hypothesize that VGCCs at the brain synapse bind to novel ligand(s) to organize the nerve terminal, due to lack of laminin[unreadable]2 at the synapses in the brain. Preliminary data suggest that extracellular interaction is important for AZ organization at the neuron-neuron synapses. Through this work, we aim to gain insight into the development/maintenance of AZs and the role of VGCCs at the synapse. These results should provide basic knowledge applicable to gain insight into the mechanism underlying the neurological disorders and age related changes.